COMPARATIVE PERFORMANCE EVALUATION OF LDPC CEDED AND TURBO CODED OFDM SYSTEMS

Abstract

OFDM (orthogonal frequency division multiplexing) is a very promising technique for high bit rate data transmission in multipath fading environment causing ISI. Coded OFDM is the modulation scheme of choice in many international standards for all forms of digital broadcasting including satellite, terrestrial and cable. Many error correcting codes have been applied to OFDM. In the field of channel coding recent era belongs to LDPC (low-density parity-check) codes. Among all practical error correction methods, Turbo codes and LDPC codes come closest to approaching the Shannon limit. In this work, comparative performance evaluation of Low Density ParityCheck (LDPC) coded and Turbo coded orthogonal frequency division multiplexing (OFDM) systems has been carried out by varying a number of parameters/factors including channel types, data block size, and number of decoding iterations. OFDM possesses the ability to counter severe channel conditions if coded with a suitable error correction scheme. LDPC coding is appearing as a promising choice in upcoming communication standards. The error rate behavior of LDPC coded OFDM system has been compared with its toughest competitor i.e. Turbo Coded OFDM system, especially on six Stanford University Interim (SUI) multipath channel models. Their computational complexities have also been worked out to evaluate the latency, efficiency, cost effect and ease of implementation. The factors that influence performance of LDPC and turbo codes have also been considered for comparison.